ATMOS 22 Ultrasonic Anemometer Installation Guide

ATMOS 22 Ultrasonic Anemometer
Installation Guide

SENSOR DESCRIPTION

The ATMOS 22 Ultrasonic Anemometer is designed for continuous monitoring of wind speed and direction (see Measurement Specifications). Ultra-low power consumption and a robust, no moving parts design that prevents errors because of wear or fouling, make the ATMOS 22 ideal for long-term, remote installations.
NOTE: The ATMOS 22 replaces the DS-2 (discontinued) and the outputs and order are not the same as the DS-2. Any DS-2 replaced by the ATMOS 22 will require data  acquisition system reprogramming based on information located in the tech note Integrators replacing DS-2 with ATMOS 22.

APPLICATIONS

• Weather monitoring
• Microenvironment monitoring
• In-canopy wind measurement
• Spatially distributed environmental monitoring
• Wind profiling
• Crop weather monitoring
• Fire danger monitoring/mapping
• Weather networks

ADVANTAGES

• Robust, no moving parts design
• Small form factor
• Low-input voltage requirements
• Low-power design supports battery-operated data loggers
• Supports the SDI-12 three-wire interface
• Tilt sensor informs user of out-of-level conditions
• No configuration necessary

PURPOSE OF THIS GUIDE
METER provides the information in this integrator guide to help ATMOS 22 Ultrasonic Anemometer customers establish communication between these sensors and their  data acquisition equipment or field data loggers. Customers using data loggers that support SDI-12 sensor communications should consult the data logger user manual.  METER sensors are fully integrated into the METER system of plug-and-play sensors, cellular-enabled data loggers, and data analysis software.

COMPATIBLE FIRMWARE VERSIONS
This guide is compatible with firmware versions 1.07 or newer.

SPECIFICATIONS

MEASUREMENT SPECIFICATIONS

Horizontal Wind Speed

Range| 0 –30 m/s
Resolution| 0.01 m/s
Accuracy| The greater of 0.3 m/s or 3% of measurement
Wind Gust

Range| 0 –30 m/s
Resolution| 0.01 m/s
Accuracy| The greater of 0.3 m/s or 3% of measurement
Wind Direction

Range| 0° –359°
Resolution| 1°
Accuracy| ±5°
Tilt
Range| –90°  to 90°
Resolution| 0.1°
Accuracy| ±1°

COMMUNICATION SPECIFICATIONS
Output
SDI-12 communication
Data Logger Compatibility
METER ZL6, Em50, and EM60 data loggers or any data acquisition systems capable of 3.6- to 15.0-VDC excitation and SDI-12 communication

PHYSICAL SPECIFICATIONS

Dimensions

Diameter| 10 cm (3.94 in)
Height| 16 cm (6.30 in), includes rain gauge filter
Operating Temperature Range
Minimum| –50 °C
Typical| NA
Maximum| 60 °C

Data Logger Compatibility
METER ZL6, Em50, and EM60 data loggers or any data acquisition systems capable of 3.6- to 15.0-VDC excitation and SDI-12 communication

Cable Length
5 m (standard)
75 m (maximum custom cable length)
NOTE: Contact Customer Support if nonstandard cable length is needed.

Connector Types
3.5-mm stereo plug connector or stripped and tinned wires stereo plug connector or stripped and tinned wires

EQUIVALENT CIRCUIT AND CONNECTION TYPES

Refer to Figure 2 and Figure 3 to connect the ATMOS 22 to a logger. Figure 2 provides a low-impedance variant of the recommended SDI-12 Specification v1.3.

PIGTAIL CABLE

NOTE: NOTE: Some early ATMOS 22 units may have the older Decagon wiring scheme where the power supply is white, the digital out is red, and the bare wire is ground.

NOTE: STEREO CABLE

SAFETY PRECAUTIONS
METER sensors are built to the highest standards, but misuse, improper protection, or improper installation may damage the sensor and possibly void the warranty. Before  integrating sensors into a sensor network, follow the recommended installation instructions and implement safeguards to protect the sensor from damaging interference.
SURGE CONDITIONS
Sensors have built-in circuitry that protects them against common surge conditions. Installations in lightning-prone areas, however, require special precautions, especially  when sensors are connected to a well-grounded third- party logger.
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CABLES
Improperly protected cables can lead to severed cables or disconnected sensors. Cabling issues can be caused by many factors, including rodent damage, driving over sensor  cables, tripping over the cable, not leaving enough cable slack during installation, or poor sensor wiring connections. To relieve strain on the connections and prevent loose  cabling from being inadvertently snagged, gather and secure the cable traveling between the ATMOS 22 and the data acquisition device to the mounting mast in one or more places.
Install cables in conduit or plastic cladding when near the ground to avoid rodent damage. Tie excess cable to the data logger mast to ensure cable weight does not cause  sensor to unplug.
SENSOR COMMUNICATIONS
METER digital sensors feature a 3-wire interface following SDI-12 protocol for communicating sensor measurements.
SDI-12 INTRODUCTION
SDI-12 is a standards-based protocol for interfacing sensors to data loggers and data acquisition equipment.
Multiple sensors with unique addresses can share a common 3-wire bus (power, ground, and data). Two-way communication between the sensor and logger is possible by  sharing the data line for transmit and receive as defined by the standard. Sensor measurements are triggered by protocol command. The SDI-12 protocol requires a unique  alphanumeric sensor address for each sensor on the bus so that a data logger can send commands to and receive readings from specific sensors.
Download the SDI-12 Specification v1.3 to learn more about the SDI-12 protocol.
DDI SERIAL INTRODUCTION
The DDI serial protocol is the method used by the METER family of data loggers for collecting data from the sensor. This protocol uses the data line configured to transmit  data from the sensor to the receiver only (simplex). Typically, the receive side is a microprocessor UART or a general-purpose IO pin using a bitbang method to receive data.  Sensor measurements are triggered by applying power to the sensor. When the ATMOS 22 is set to address 0, a DDI serial string is sent on power up, identifying the sensor.
INTERFACING THE SENSOR TO A COMPUTER
The serial signals and protocols supported by the sensor require some type of interface hardware to be compatible with the serial port found on most computers (or USB-to- serial adapters). There are several SDI-12 interface adapters available in the marketplace; however, METER has not tested any of these interfaces and cannot make a  recommendation as to which adapters work with METER sensors. METER data loggers and the ZSC and PROCHECK handheld devices can operate as a computer-to- sensor interface for making on-demand sensor measurements. For more information, please contact NORTH AMERICA.
METER SDI-12 IMPLEMENTATION
METER sensors use a low-impedance variant of the SDI-12 standard sensor circuit (Figure 2). During the power-up time, sensors output some sensor diagnostic information  and should not be communicated with until the power-up time has passed. After the power up time, the sensors are compatible with all commands listed in the  SDI-12 Specification v1.3 except for the continuous measurement commands ( aR0 – aR9 and aRC0 – aRC9 ). M , R , and C command implementations are found on page  7.
Out of the factory, all METER sensors start with SDI-12 address 0 and print out the DDI serial startup string during the power-up time. This can be interpreted by non- METER SDI-12 sensors as a pseudo-break condition followed by a random series of bits.
The ATMOS 22 will omit the DDI serial startup string (sensor identification) when the SDI-12 address is nonzero.
Changing the address to a nonzero address is recommended for this reason.

ATMOS 22 INTERNAL MEASUREMENT SEQUENCE
Upon power up, the ATMOS 22 initializes an internal timer to 55. This internal timer is incremented by 1 every second and resets to 0 after incrementing to 59. In addition,  issuing an averaging command ( aM! , aR0! , aR3! , and aC! ) resets this timer to 55.
While powered up, the ATMOS 22 takes wind and air temperature measurements every 10 s at internal timer intervals of 0, 10, 20, 30, 40, 50 and logs these values internally.  Orientation is measured every 60 s at the internal timer interval of 4 and logged internally. The aR4! command will output instantaneous measurements of these parameters.
The aM! , aR0! , aR3! , and aC! commands (and subsequent D commands when necessary) will compute and output the averages, accumulations, or maximums of these  measurements (and derived measurements) and reset internal averaging counters and accumulators.
Therefore, it is not necessary to oversample the ATMOS 22 and compute averages, accumulations, and maximums in external data systems. Less frequent sampling has the additional benefit of decreasing data acquisition systems and ATMOS 22  power consumption. If the aM! , aR0! , aR3! , and aC! commands are issued more frequently than 2 times their measurement interval, the ATMOS 22 will not average the  measurements and will output instantaneous values. The ATMOS 22 has two error codes available—general error code –9999 and invalid wind measurement error code – 9990 .

SDI-12 CONFIGURATION

Table 1 lists the SDI-12 communication configuration.

SDI-12 TIMING
All SDI-12 commands and responses must adhere to the format in Figure 4 on the data line. Both the command and response are preceded by an address and terminated by  a carriage return line feed combination and follow the timing shown in Figure 5.

COMMON SDI-12 COMMANDS
This section includes tables of common SDI-12 commands that are often used in an SDI-12 system and the corresponding responses from METER sensors.
IDENTIFICATION COMMAND ( aI! )
The Identification command can be used to obtain a variety of detailed information about the connected sensor. An example of the command and response is shown in  Example 1, where the command is in bold and the response follows the command.
Example 1 1I!113METER ␣ ␣ ␣ ATM22 ␣ 100631800001

Parameter| Fixed Character
Length| Description
---|---|---
1I!| 3| Data logger command
Request to the sensor for information from sensor address 1.
1| 1| Sensor address
Prepended on all responses, this indicates which sensor on the bus is returning the
following information.
13| 2| Indicates that the target sensor supports SDI-12 Specification v1.3
METER␣ ␣ ␣| 8| Vendor identification string
( METER  and three spaces ␣ ␣ ␣ for all METER sensors)
 ATM22 ␣| 6| Sensor model string
This string is specific to the sensor type. For the ATMOS 22, the string is ATM22  ␣.
100| 3| Sensor version
This number divided by 100 is the METER sensor version (e.g., 100 is version 1.00).
6.32E+08| ≤13,
variable| Sensor serial number
This is a variable length field. It may be omitted for older sensors.

CHANGE ADDRESS COMMAND ( aAB! )
The Change Address command is used to change the sensor address to a new address. All other commands support the wildcard character as the target sensor address except  for this command. All METER sensors have a default address of 0 (zero) out of the factory. Supported addresses are alphanumeric (i.e., a – z , A – Z , and 0 – 9 ). An  example output from a METER sensor is shown in Example 2, where the command is in bold and the response follows the command.

ADDRESS QUERY COMMAND (?!)
While disconnected from a bus, the Address Query command can be used to determine which sensors are currently being communicated with. Sending this command over a  bus will cause a bus contention where all the sensors will respond simultaneously and corrupt the data line. This command is helpful when trying to isolate a failed sensor.  Example 3 shows an example of the command and response where the command is in bold and the response follows the command. The question mark ( ? ) is a wildcard  character that can be used in place of the address with any command except the Change Address command.

Parameter| Fixed
CharacterLength| Description
---|---|---
 ?!| 2| Data logger command.
Request for a response from any sensor listening on the data line.
0| 1| Sensor address.
Returns the sensor address to the currently connected sensor.

COMMAND IMPLEMENTATION
The following tables list the relevant Measurement ( M ), Continuous ( R ), and Concurrent ( C ) commands and subsequent Data ( D ) commands when necessary.
MEASUREMENT COMMANDS IMPLEMENTATION
Measurement ( M ) commands are sent to a single sensor on the SDI-12 bus and require that subsequent Data ( D ) commands are sent to that sensor to retrieve the sensor  output data before initiating communication with another sensor on the bus.
Please refer to Table 2 and Table 3 for an explanation of the command sequence and see Table 9 for an explanation of response parameters.

Table 2 aM! command sequence

NOTE: This command reports average or maximum values.
 aM!| atttn
 aD0!| a+++
 aD1!| a±

NOTE: The measurement and corresponding data commands are intended to be used back to back. After a measurement command is processed by the sensor, a service  request a is sent from the sensor signaling the measurement is ready. Either wait until ttt seconds have passed or wait until the service request is received before  sending the data commands. See the SDI-12 Specifications v1.3 document for more information.

CONTINUOUS MEASUREMENT COMMANDS IMPLEMENTATION
Continuous ( R ) measurement commands trigger a sensor measurement and return the data automatically after the readings are completed without needing to send a D  command.
The aR3! and aR4! commands must be used at intervals of 10 s or greater for the response to be returned within 15 ms as defined in the SDI-12 standard.
Please refer to Table 4 through Table 7 for an explanation of the command sequence and see Table 9 for an explanation of response parameters.

CONCURRENT MEASUREMENT COMMANDS IMPLEMENTATION
Concurrent (C) measurement commands are typically used with sensors connected to a bus. Measurements are initiated with a C command and subsequent D commands are  sent to the sensor to retrieve the readings.
Please refer to Table 8 for an explanation of the command sequence and Table 9 for an explanation of response parameters.

2. ttt| s| Maximum time measurement will take (fixed width of 3) | —| Tab character | —| Carriage return character | —| Line feed character | m/s| Wind speed from the northerly direction (negative values denote southerly direction) (average since the last measurement or instantaneous value depending on SDI-12 command used) | m/s| Wind speed from the easterly direction (negative values denote westerly direction) (average since the last measurement or instantaneous value depending on SDI-12 command used) | m/s| Combined wind speed magnitude of the and (average since the last measurement or instantaneous value depending on 501-12 command used) | m/s| Maximum measured since the last measurement | 0| Wind heading clockwise from north reference (average since the last measurement or instantaneous value depending on 501-12 command used) | °C| Air temperature (not a true air temperature as it is not corrected for solar radiation) (average since the last measurement or instantaneous value depending on 01-12 command used) | 0| X orientation angle (0 is level) (last measured value) | 0| Y orientation angle (0 is level) (last measured value) | —| This parameter is reported as 0. Previous firmware versions reported a compass heading, which has been removed. | —| ASCII character denoting the sensor type For ATMOS 22, the character is the right square bracket ] character | —| METER serial checksum <01C>| —| METER serial 6-bit CRC

SERIAL CHECKSUM
These checksums are used in the continuous commands R3 and R4 . The legacy checksum is computed from the start of the transmission to the sensor identification  character, excluding the sensor address.
Legacy checksum example input is 0.26 1.27 0.37 23.1 3.2 4.8 0\Hg and the resulting checksum output is H .

The more robust CRC6 , if available, utilizes the CRC-6-CDMA2000-A polynomial with the value 48 added to the results to make this a printable character and is computed  from the start of the transmission to the legacy checksum character, excluding the senor address.
CRC6 checksum example input is 0.26 1.27 0.37 23.1 3.2 4.8 0\Hg and the resulting checksum is the character g .

CUSTOMER SUPPORT

NORTH AMERICA
Customer service representatives are available for questions, problems, or feedback Monday through Friday, 7:00 am to 5:00 pm Pacific time.

Email:| support.environment@metergroup.com
sales.environment@metergroup.com
---|---
Phone:| +1.509.332.5600
Fax:| +1.509.332.5158
Website:| metergroup.com

EUROPE
Customer service representatives are available for questions, problems, or feedback Monday through Friday, 8:00 to 17:00 Central European time.

Email:| support.europe@metergroup.com
sales.europe@metergroup.com
---|---
Phone:| +49 89 12 66 52 0
Fax:| +49 89 12 66 52 20
Website:| metergroup.de

If contacting METER by email, please include the following information:

NOTE: For products purchased through a distributor, please contact the distributor directly for assistance.
REVISION HISTORY
The following table lists document revisions.

Removed 20-s limitation of aM!, aR0!, and aR3!.
1| 11.15.2017| 1| Added information for DS-2 update to ATMOS 22.
0| 10.27.2017| 1| Initial release.

References

• METER Group
• METER Group

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